1. Field of the Invention
The present invention relates to a hose device for fuel transportation. In particular, the present invention relates to a hose device for fuel transportation used for transporting a methanol fuel, the device composed of a hose and a connector.
2. Description of the Art
In recent years, accompanying environmental issues and depletion issues of petroleum, developments of fuel-cell vehicles as next-generation vehicles have been actively pursued. The fuel-cell vehicle uses hydrogen gas as an ultimate fuel. However, since hydrogen is a gas, there are problems in handling and in construction, maintenance, and the like of the infrastructure. Therefore, vehicle-mounted systems, in which liquid fuels are reformed into hydrogen, so as to generate hydrogen, have been researched. As the liquid fuel, methanol has been primarily researched because methanol can be reformed into hydrogen with relative ease. The system using the aforementioned methanol as a fuel is, for example, a system in which methanol is transferred from a methanol storage tank 15 to a reformer 17 through a fuel hose 16, and hydrogen produced by reformation with the reformer 17 is transferred to a fuel-cell stack 18 and, therefore, is made available for electric power generation, as shown in FIG. 4. Furthermore, the aforementioned methanol has been researched as a fuel alternative to gasoline because of a cleaner exhaust gas, and some of them have been in practical use.
However, when fuel transportation hoses generally used for gasoline are used for a methanol fuel, since methanol has permeability higher than that of gasoline, methanol permeates through hoses by a large degree. From the viewpoint of environmental issues, in California, USA, there is a regulation of HC (hydrocarbon gas) emission from vehicles as of now, and there is a tendency to get tougher regulations. Likewise, in Japan and Europe, regulations of HC emission similar to that in California have become into operation. Therefore, the permeation of methanol through the hose is a significant problem, and the amount of permeation thereof must be suppressed. Furthermore, the problem of methanol permeation relates to not only the fuel transportation hose. There are fears of problems due to methanol permeation similar to that described above with respect to a joint portion of a methanol storage tank and a hose, and a joint portion of the hose and the reformer.
In addition to the requirement for the methanol permeation resistance as described above, the following characteristics have been required. That is, gasoline and methanol have different polarities from each other, and the hose is swelled with methanol by a large degree, so that degradation of the hose is accelerated. There are fears of problems in that, for example, significant amounts of materials are extracted from the components used for forming the hose, and these extracted materials may cause malfunctions, such as clogging, or the extracted materials are transferred to the reformer together with methanol so as to cause degradation of the performance of the reformer due to poisoning by the extracted materials. Consequently, superior methanol resistance and superior non-extractability with methanol are required for the hose. Since methanol exhibits hydrophilicity, there is a high possibility that the content of water increases by a large degree. Therefore, the hose is required to have water resistance. When methanol is used as a fuel, as described above, the fuel transportation hose is joined with the reformer, and the temperature in the periphery of the reformer becomes very high, so that heat resistance is required for the hose. Furthermore, since the energy density of methanol is somewhat lower than that of gasoline, there is a possibility that the supply pressure of methanol may be increased in order to increase the amount of flow and, therefore, the hose is required to have significant pressure resistance.
The present invention was made in consideration of the aforementioned circumstances. Accordingly, it is an object of the present invention to provide a hose device for fuel transportation having superior methanol permeation resistance, methanol resistance, non-extractability with methanol, water resistance, heat resistance, pressure resistance, etc., when methanol is used as the fuel being transported.
In order to achieve the aforementioned object, a hose device for fuel transportation according to the present invention comprises a hose main body, in which at least the innermost layer is made of a resin having methanol permeation resistance, and a quick connector mounted on at least one end portion of the hose main body. The hose device has a structure in which the aforementioned quick connector is composed of a nearly cylindrical housing section and a pair of O-rings, the aforementioned housing section being composed of a material having methanol permeation resistance. In the connector, one end portion of the housing section is formed as an insert portion to be inserted into the aforementioned hose main body, the other end portion being formed as a container portion for containing an engagement target member therein. A first O-ring of the pair of O-rings for the connector is composed of at least one of fluororubber and ethylene-propylene rubber and is mounted on the inner radius surface, at the hose insert portion side, in the aforementioned container portion, and a second O-ring of the pair of O-rings is composed of butyl rubber and is mounted on the inner radius surface, at the outlet side, in the aforementioned container portion.
That is, the inventors of the present invention carried out research regarding fuel transportation hoses having superior methanol permeation resistance, methanol resistance, non-extractability with methanol, water resistance, heat resistance, and pressure resistance when methanol is used as the fuel, and in addition to the above, earnestly carried out research regarding connectors themselves mounted on the aforementioned hoses in order to join the hoses with other component. As a result, it was found out that by adopting the configuration in which at least the innermost layer of the hose main body was made of the resin having methanol permeation resistance, and in the quick connector mounted on at least one end portion of the hose main body, the housing section is formed from a material having methanol permeation resistance, the first O-ring is composed of at least one of fluororubber and ethylene-propylene rubber is mounted on the inner radius surface, at the hose insert portion side, in the container portion of the aforementioned quick connector, and the second O-ring is composed of butyl rubber mounted on the inner radius surface, at the outlet side, in the aforementioned container portion, each of the hose main body and the quick connector exhibited superior methanol permeation resistance, methanol resistance, non-extractability with methanol, and water resistance. Further, since two O-rings made of different materials are provided in the container portion of the quick connector, the joint portion of the hose and the quick connector have methanol resistance, and in addition to this, high airtightness. As a consequence, the present invention has been achieved.
When the material having methanol permeation resistance and constituting the aforementioned housing section is a stainless steel, the methanol permeation resistance is further improved.
When the aforementioned first O-ring is formed from ethylene-propylene rubber produced by peroxide vulcanization without the use of zinc oxide, extraction of zinc by methanol does not occur, and problems such as the degradation of performance of the reformer due to poisoning with the extracted materials can be suppressed.
When the aforementioned first O-ring is formed from ternary fluororubber having a fluorine content of 69% by weight or more, swelling of the fluororubber (FKM) with methanol is suppressed, superior sealing property can be stably ensured, and in addition, the poisoning of the reformer can be suppressed because the FKM has superior non-extractability.
When the resin having methanol permeation resistance and constituting the aforementioned hose main body is a fluororesin, the balance of performance, for example, methanol permeation resistance, is further improved.
When the aforementioned hose main body is a hose having a three-layer structure, in which the innermost layer is composed of conductive ethylene-tetrafluoroethylene copolymer, the intermediate layer is composed of non-conductive ethylene-tetrafluoroethylene copolymer, and the outermost layer is composed of polyamide, problems which may be brought about by static electricity generated when methanol flows tend to be avoided.